I have read that when a wood flute or clarinet has a crack in it, that to repair it a hole is drilled at each end of the crack to prevent the crack from going farther. I understand that, but would like to know what kind of pin they put in the hole. Is it metal or the same kind of wood the instrument is made of?
I’ve seen alot of photos of antique flutes with pinned cracks and they all appear to have metal pins. Looks like a pain in the butt to do. Jon C can probably give you some good advice on repairing cracks…he restores and repairs old flutes.
There are numerous approaches to repairing cracks. Pinning is one option; waiting 'til it “settles” and glueing is another; opening the crack as wide as it’ll go by putting the instrument in a warm dry place and then filling it is yet another – it depends on the crack, really.
(And of course, let’s not forget the time-honored beeswax, hoseclamps or electrical-tape methods …)
A teacher told me once about someone drilling pinholes at the ends of a lengthening crack to stop it expanding any farther, but that was used as a literal “stopgap” measure until the crack settled and could then be filled.
Bottom line (IMO) … If you have a cracked instrument, try talking to your local general woodwind repairer first – I know it took me a while to appreciate that option, but hey, those guys work on oboes and bassoons and clarinets all the time – and then get a second opinion from someone else. (But don’t be surprised if they suggest different methods! 
)
From an engineering basis, drilling a hole at each end of a crack is sound. Cracks grow from the stresses which build up at sharp points (which is why aeroplane bodies have rounded windows). A round hole will spread any stresses over a wider area, so might stop a crack lengthening. Repairing it is a different matter!
Chris
I’m learning as I go along…
I have a recent ebay flute that came with a HJ crack. Once I buffed it out I have been breaking it in and keeping it in my flute-humidor.
The crack as almost closed completely on its own… and the rings stay on now.
It may close all the way yet.
Every situation is different, I’m sure, so your mileage may vary. Its something to consider.
I will have to agree on the proper path repair to be stabilization first.
Putting it in an oven though.
I can’t think that would be good on a finished flute, but I may be wrong.
Ive had it explained to me that pulling the liner, clampling and gluing the crack then re-reaming to the original I.D. to fit the liner is probably the most permanent fix.
I believe this is Terry’s method and I think Jon C. does this too.
Makes sense.
Although I imagine you’ll loose some chimney hight on the emb. but its probably negligible.
If the crack is too large I guess filling or making a new HJ is the only other solution.
I dunno… like I said. Im learning. Its fun I must admit.
As mentioned, beeswax works as quick repair.
Training the bees takes a lot of time though.
There are two approaches: one is to correct the problem, why it is cracking, the other is to just address the symptoms and try to make it look like it is repaired. Like Terry says in his website, the wood shrinks the metal liner does not. The only way to repair a crack in the head or barrel so it won’t re-open is to relieve the pressure built up by the shrinking wood. This entails removing the sleeve, shrinking the wood, (I use a convection oven), closing the crack, re-reaming the bore, and re-gluing the liner. Even if you were to stop the crack from spreading you will still have a lot of pressure on it to open more. I would not recommend wax or other goop in the crack, as then when you get the thing repaired, the goop will have to be cleaned from the crack, so the glue will stick. 
Most of my hardest restoration jobs is fixing previous bad repairs to the flute! They did some real doosies back about 100 years ago, big metal bands cut into the wood, Frankenstein pin stitches, etc. Superglue is a good temp. repair, as it can be cleaned out later when you want the job done right.
My 2 bits worth…
AHHH! OK, now I understand about the oven.
Hmmm… I thought you told me wax was ok? 
Like I said… I’m learning.
Wooden flutes are a different beast. Wood, unlike aluminum, is not mechanically isotropic. And unlike airplanes, the kind of vibration flutes are subject to are several orders of magnitude less.
Pinning is ugly (imagine stitches that never go away), at least the examples I’ve seen online, and seems like a band-aid solution to me. I’ve fixed two cracked flute headjoints following Terry McGee’s description and the glue is almost invisible.
Here is my latest project, it is a J Wallis (Frankeinstien head!) Nice crown…
This is what I am talking aobut previous repairs! The barrel is covered with a beautiful metal covering. (not)
Stay tuned, to see the results. 
Well as they say, “Pictures speak louder then words”
Here is the same head after a little repair work… Still have a little more detail work on the Emb. hole, but it is coming along.
The barrel is next, when I cut off the metal clading, the maker stamp is perfectly perserved under the metal. 
Um, wow. Nice work.
Did you re-cut the embouchure? It looks cleaned up.
The emb hole was a mess, I dressed it up a little. I still have a little fine tuning on it, but will wait until the rest of the flute catches up… Another thing about closing the crack, is that it also brings the emb hole back into it’s original shape. Sometimes they will look round, and when you close the crack the emb hole will turn ack to oval.
Holy extreme makeover–Nice work!
nice repair work!
as far as repairs using glue to close cracks… is super glue or wood glue better? is one likely to hold longer or mean there will be a smaller chance of further cracking because it gives more?
Sara
wood glue? you mean white or yellow glue? they’re water soluble.
you can get water resistant wood glue.
Super glue is the glue I’ve always heard mentioned by makers and instrument repair folks. I’ve used it in the past, and it’s removable for future repairs if necessary.
Eric
Thank you all for your input.
Superglue. The runniest you can find, according to Mr. Skelton. It’s also buffable, and removable with acetone.
I use a high grade of super glue, like Cathy said the thinnest. If it is a hairline crack, one technique is to hook up a vacuum to the end of the flute, plug all the holes and suck the glue into the crack. It just sucks it right in. I use scotch tape, and tape itas close to the crack as I can, then mound some fine blackwood dust in the crack and apply the glue, remove the tape right away, when the glue is still wet. a razor knife to scrape off excess glue and the any spills can be cleaned with debonder.